Rotor and electric vehicle

ABSTRACT

A rotor includes a rotor core fixedly attached to a rotational shaft and having a plurality of hole portions arranged in the circumferential direction, a magnet inserted into a plurality of hole portions each, and a filling portion injected into the hole portion. The filling portion is injected into the hole portion from a gate facing a central part in the width direction of the magnet in the opening of the hole portion.

TECHNICAL FIELD

The present invention relates to a rotor and an electric vehicle, andparticularly to a rotor using a filler to secure a magnet to a rotorcore as well as an electric vehicle including the rotor.

BACKGROUND ART

Japanese Patent Laying-Open No. 2002-034187 (Patent Document 1)discloses a rotor in which a resin material fills a space between a holeprovided in a rotor core and a permanent magnet embedded in the hole soas to secure the permanent magnet to the rotor core.

Japanese Patent Laying-Open No. 2001-352702 (Patent Document 2)discloses an outer rotor having an adhesive pool in an end portion inthe width direction of a magnetized surface of a magnet.

Japanese Patent Laying-Open No. 2004-357347 (Patent Document 3)discloses a rotor in which a groove is provided in an end plate for thepurpose of avoiding a caulked portion of a laminated steel.

Japanese Patent Laying-Open No. 2002-354722 (Patent Document 4)discloses a rotor in which a caulked portion of a laminated steel isprovided inward in the radial direction with respect to a permanentmagnet.

In the rotor disclosed in Patent Document 1, the rotor core includesanother hole for injecting a resin therefrom in addition to the holeinto which the magnet is inserted. As a result, the strength of therotor core could be deteriorated, or there could be any influence on themagnetic characteristic, in some cases. In addition, downsizing of therotor is hindered.

In the rotor disclosed in Patent Document 2, a central portion in thewidth direction of the magnet is supported by the rotor core on theouter peripheral side of the rotor core, and thus a stress generated onthe rotor core at this portion increases.

In the case where a groove is provided in an end plate as disclosed inPatent Document 3, the surface pressure between the rotor core and theend plate could be excessively increased in some cases. Patent Document4 does not disclose a structure with which this problem can besufficiently solved.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a rotor that isdownsized and has a high durability as well as an electric vehicleincluding the rotor.

A rotor according to the present invention includes: a rotor corefixedly attached to a rotational shaft and having a plurality of holeportions arranged in a circumferential direction; a magnet inserted intothe plurality of hole portions each; and a filling portion injected intothe hole portion. The filling portion is injected into the hole portionfrom a portion facing a central part in a width direction of the magnetin an opening of the hole portion.

Here, regarding the rotor of the present invention, “filling portion”refers to a portion intended to secure the magnet to the rotor core, notby adhesion but chiefly by filling the inside of the hole portion.

In the above-described structure, when the filling portion is injected,the magnet can be stably pressed opposite in the radial direction,relative to the portion where the filling portion is injected.Therefore, the precision in balance of the magnets arranged in thecircumferential direction is improved. Further, since the fillingportion is injected from the opening of the hole portion, a separatehole portion for injecting the filling portion therefrom is unnecessary.Accordingly, deterioration in strength can be suppressed to improve thedurability of the rotor, and the rotor can be downsized.

In the rotor, preferably the hole portion includes an extension in aportion facing a corner of the magnet, for helping spread of the fillingportion.

In this way, the spread of the filling portion into this extension canbe helped.

In the rotor, preferably the filling portion is injected into the holeportion from a portion facing a central part of a side of the magnet,the side being located inward in a radial direction of the rotor core.

Thus, when the filling portion is injected, the magnet can be pressedoutward in the radial direction. Therefore, the side surface locatedoutward in the radial direction of the magnet and the rotor core can beallowed to contact each other uniformly. As a result, the centrifugalforce acting on the magnet when the rotor is rotated can be dispersedmore uniformly and transmitted to the rotor core, and thus thedurability of the rotor is improved.

In the rotor, preferably the hole portion includes an outer extensionfacing a corner of the magnet that is located outward in the radialdirection, for helping spread of the filling portion. More preferably,outer extensions and inner extensions for helping spread of the fillingportion are provided in respective portions facing four corners in anaxial cross section of the magnet in the hole portion.

In this way, the spread of the filling portion into the extensions canbe helped.

Preferably, the rotor further includes an end plate provided on an axialend surface of the rotor core. The rotor core is formed of a laminatedsteel. On the axial end surface of the rotor core, a first projectionlocated at a caulked portion of the laminated steel and a secondprojection located at a portion where the filling portion is injectedare formed. The first projection and the second projection aresubstantially concentrically provided such that a common groove foravoiding the first projection and the second projection can be formed inthe end plate.

In the above-described structure, excessive increase of the surfacepressure between the rotor core and the end plate is suppressed whileinterference between the end plate and the first and second projectionscan be avoided.

An electric vehicle according to the present invention includes therotor as described above.

Thus, the electric vehicle including the rotor exhibiting a high thermaldissipation property of the magnet can be obtained.

In accordance with the present invention as described above, the rotorcan be downsized and the durability can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing a structure of a drive unit towhich a rotor according to an embodiment of the present invention isapplied.

FIG. 2 is a plan view of a rotor according to an embodiment of thepresent invention.

FIG. 3 is an enlarged view showing a magnet-inserted portion andtherearound in the rotor shown in FIG. 2.

FIG. 4 is a longitudinal cross section of the rotor shown in FIG. 2.

BEST MODES FOR CARRYING OUT THE INVENTION

In the following, a description will be given of an embodiment of arotor and an electric vehicle based on the present invention. Here, likecomponents are denoted by like reference characters and a descriptionthereof will not be repeated in some cases.

FIG. 1 is a diagram schematically showing a structure of a drive unit towhich a rotor according to an embodiment of the present invention isapplied. In the example shown in FIG. 1, drive unit 1 refers to a driveunit mounted on a hybrid vehicle that is “electric vehicle” and isconfigured to include a motor generator 100, a housing 200, a reductionmechanism 300, a differential mechanism 400, and a driveshaft receivingportion 500.

Motor generator 100 is a rotating electric machine having the functionof an electric motor or electric generator, and includes a rotationalshaft 120 rotatably attached to housing 200 via a bearing 110, a rotor130 attached to rotational shaft 120, and a stator 140. Stator 140includes a stator core 141, and a coil 142 is wound around stator core141. Coil 142 is electrically connected to a feed cable 600A via aterminal block 210 provided to housing 200. Feed cable 600A has anotherend connected to a PCU 600. PCU 600 is electrically connected to abattery 700 via a feed cable 700A. Accordingly, battery 700 and coil 142are electrically connected.

The motive energy that is output from motor generator 100 is transmittedfrom reduction mechanism 300 via differential mechanism 400 todriveshaft receiving portion 500. The drive force transmitted todriveshaft receiving portion 500 is transmitted in the form of arotational force via a driveshaft (not shown) to wheels (not shown) tocause the vehicle to run.

In contrast, when the hybrid vehicle is regeneratively braked, thewheels are rotated by an inertial force of the vehicle body. Therotational force from the wheels drives motor generator 100 viadriveshaft receiving portion 500, differential mechanism 400 andreduction mechanism 300. At this time, motor generator 100 operates asan electric generator. The electric power generated by motor generator100 is stored in battery 700 via an inverter in PCU 600.

Feed cables 600A, 700A are each a three-phase cable formed of a U phasecable, a V phase cable and a W phase cable. Coil 142 is formed of a Uphase coil, a V phase coil and a W phase coil, and respective terminalsof these three coils are connected to feed cables 600A, 700A that areeach the three-phase cable.

The use of motor generator 100 is not limited to a hybrid vehicle (HV)and may be mounted on other “electric vehicles” (such as fuel cellvehicle and electric vehicle for example).

FIG. 2 is a plan view of rotor 130. FIG. 3 is an enlarged view showing amagnet-inserted portion and therearound in rotor 130. FIG. 4 is alongitudinal cross section of rotor 130. Referring to FIGS. 2 to 4,rotor 130 includes a rotor core 131 fixedly attached to rotational shaft120 and having a plurality of hole portions 131A arranged in thecircumferential direction, a magnet 132 inserted into a plurality ofhole portions 131A each to be embedded in rotor core 131, a resinportion 133 filling a space between the side surface of hole portion131A and magnet 132, and an end plate 134 provided on an end surface inthe axial direction of rotor core 131.

Resin portion 133 that is “molded resin portion” is formed including anepoxy-based resin for example. Resin portion 133 is thus provided tosecure magnet 132 to rotor core 131. Resin portion 133 secures magnet132 to rotor core 131 not by means of adhesion but chiefly by fillingthe inside of hole portion 131A. Therefore, the ratio of filling resinportion 133 to the space in hole portion 131A is higher than the ratioof an adhesive used as a securing material for the magnet in a similarrotor core. In this way, magnet 132 can be precisely fixed in holeportion 131A. Here, resin portion 133 is poured from an opening of holeportion 131A into hole portion 131A without providing a special hole forinjecting the resin therefrom. Accordingly, rotor 130 can be downsized.

Rotor core 131 includes a plurality of hole portions 131A arranged inthe circumferential direction. Magnets 132 are inserted into a pluralityof hole portions 131A respectively. Filling portion 133 is injected intohole portion 131A from a portion (gate 1330, see FIG. 3) facing acentral part of a side of the magnet. The side of the magnet refers tothe side located inside in the radial direction of rotor core 131, inthe opening of hole portion 131A.

Attention is now given to the presence of a clearance between holeportion 131A and magnet 132. In the case for example where an adhesiveis used to secure magnet 132, movement of magnet 132 in hole portion131A cannot be controlled and accordingly difference between respectivepositions in the radial direction of magnets 132 occurs (namely theprecision in balance is deteriorated). Further, in the case wheremagnets 132 are dominantly located inside in the radial direction inrespective hole portions 131A, magnets 132 could be bent, depending onthe ratio of the filling adhesive, due to a centrifugal force actingwhen the rotor is rotated, resulting in a local large stress on rotorcore 131. In contrast, resin portion 133 is injected as described abovefrom gate 1330 located at the central part of the magnet that is locatedinside in the radial direction of rotor core 131, and thus magnet 132can be stably pressed outward in the radial direction of rotor core 131when the resin is injected and accordingly the above-described problemcan be solved.

Further, in rotor 130, hole portion 131A includes outer extensions1310A, 1310B each in a portion facing a corner of magnet 132 that islocated outward in the radial direction (the direction of an arrow DR1),for the purpose of helping the spread of filling portion 133, andincludes inner extensions 1310C, 1310D each in a portion facing a cornerof magnet 132 that is located inward in the radial direction (thedirection of an arrow DR2), for the purpose of helping the spread offilling portion 133.

In the case as described above where resin portion 133 is injected frominside in the radial direction of the magnet, the resin spreads mosthard around the outer corners in the radial direction of the magnet.Here, outer extensions 1310A and 1310B are provided at the corners, sothat the spread of the resin portion can be efficiently helped withoutproviding a hole for injecting the resin in addition to hole portion131A.

As shown in FIG. 4, rotor core 131 is formed by superposing sheets of amagnetic material such as iron or an iron alloy into a laminated body.From an end surface in the axial direction of rotor core 131, a caulkedportion 1310 of the laminated steel as well as a gate 1330 where theresin remains at the portion from which the filling portion is injectedprotrude. On the axial end surface of rotor core 131, end plate 134 isprovided. In end plate 134, a groove 1340 for avoiding interference withcaulked portion 1310 and gate 1330 is formed. Here, caulked portion 1310and gate 1330 are provided in close proximity to each other(substantially concentrically) such that interference with the end platecan be avoided by means of the common groove 1340. Thus, caulked portion1310 and gate 1330 can be housed in groove 1340 without making groove1340 excessively large. Therefore, while an excessive increase of thesurface pressure between rotor core 131 and end plate 134 is suppressed,interference between end plate 134 and caulked portion 1310 and gate1330 can be avoided. Preferably, the width (L2) of groove 1340 isapproximately not more than 15% of the width (L1) of rotor core 131(more preferably approximately not more than 10% thereof). Groove 1340as described above is provided so that the surface pressure of end plate134 is slightly increased and the degree of flatness of the axial endsurface of rotor core 131 is improved.

In the description above, the example is explained where gate 1330 isprovided in the portion facing the central part of the side of themagnet that is located inward in the radial direction of rotor core 131,in the opening of hole portion 131A. Alternatively, gate 1330 may beprovided in a portion facing a central part of a side of the magnet thatis located outward in the radial direction of rotor core 131. Further,in the description above, the example is explained where outerextensions 1310A, 1310B and inner extensions 1310C, 1310D are provided.Instead, only one of outer extensions 1310A, 1310B and inner extensions1310C, 1310D may be provided.

The description above is summarized as follows. Namely, rotor 130according to the present embodiment includes rotor core 131 fixedlyattached to rotational shaft 120 and having a plurality of hole portions131A arranged in the circumferential direction, magnets 132 insertedrespectively into a plurality of hole portions 131A, and filling portion133 injected into hole portions 131A. Filling portion 133 is injectedinto hole portion 131A from a portion facing a central part in the widthdirection of magnet 132 in an opening of hole portion 131A.

Further, in rotor 130, hole portion 131A includes outer extensions1310A, 1310B each in a portion facing a corner of magnet 132 that islocated opposite in the radial direction (namely located outward in theradial direction) relative to the position where filling portion 133 isinjected, for the purpose of helping the spread of filling portion 133.In addition, in rotor 130, inner extensions 1310C, 1310D are providedeach in a portion facing a corner of magnet 132 that is located inwardin the radial direction, for the purpose of helping the spread offilling portion 133. Namely, in rotor 130 of the present embodiment,(outer/inner) extensions 1310A to 1310D helping the spread of fillingportion 133 are provided in respective portions facing the four cornersof an axial cross section of magnet 132 in hole portion 131A.

Moreover, in rotor 130, on the end surface in the axial direction ofrotor core 131 formed of a laminated steel, caulked portion 1310 of thelaminated steel that is “first projection” as well as gate 1330 that is“second projection” located at the portion from which the fillingportion is injected are formed. Caulked portion 1310 and gate 1330 areprovided substantially concentrically such that common groove 1340 foravoiding the caulked portion and the gate can be formed in end plate134.

In the rotor of the present embodiment, when filling portion 133 isinjected, magnet 132 is pressed opposite, in the radial direction, tothe position where filling portion 133 is injected. Therefore, theprecision in balance of magnets 132 arranged in the circumferentialdirection of rotor 130 is improved. In particular, in the case wherefilling portion 133 is injected from a portion facing a central part ofa side of magnet 132 that is located inward in the radial direction ofrotor core 131, magnet 132 can be pressed outward in the radialdirection when filling portion 133 is injected, so that rotor core 131and a side located outward in the radial direction of magnet 132 can beuniformly brought into contact with each other. Accordingly, thecentrifugal force acting on magnet 132 while the rotor is rotating canbe more uniformly dispersed and transmitted to rotor core 131. Further,since filling portion 133 is injected from an opening of hole portion131A, a separate hole for injecting filling portion 133 is unnecessary.Thus, deterioration of the strength can be suppressed to improve thedurability of rotor 130 and rotor 130 can be downsized.

It should be construed that embodiments disclosed above are by way ofillustration in all respects, not by way of limitation. It is intendedthat the scope of the present invention is defined by claims, andincludes all modifications and variations equivalent in meaning andscope to the claims.

INDUSTRIAL APPLICABILITY

The present invention is applicable for example to a rotor and anelectric vehicle.

1. A rotor comprising: a rotor core fixedly attached to a rotationalshaft and having a plurality of hole portions arranged in acircumferential direction; a magnet inserted into said plurality of holeportions each; and a filling portion injected into said hole portion,said filling portion being injected into said hole portion from aportion facing a central part in a width direction of said magnet in anopening of said hole portion.
 2. The rotor according to claim 1, whereinsaid hole portion includes an extension in a portion facing a corner ofsaid magnet, for helping spread of said filling portion.
 3. The rotoraccording to claim 1, wherein said filling portion is injected into saidhole portion from a portion facing a central part of a side of saidmagnet, said side being located inward in a radial direction of saidrotor core.
 4. The rotor according to claim 3, wherein said hole portionincludes an outer extension facing a corner of said magnet that islocated outward in the radial direction, for helping spread of saidfilling portion.
 5. The rotor according to claim 1, wherein outerextensions and inner extensions for helping spread of said fillingportion are provided in respective portions facing four corners in anaxial cross section of said magnet in said hole portion.
 6. The rotoraccording to claim 1, further comprising an end plate provided on anaxial end surface of said rotor core, wherein said rotor core is formedof a laminated steel, on said axial end surface, a first projectionlocated at a caulked portion of said laminated steel and a secondprojection located at a portion where said filling portion is injectedare formed, and said first projection and said second projection aresubstantially concentrically provided such that a common groove foravoiding said first projection and said second projection can be formedin said end plate.
 7. An electric vehicle comprising the rotor asrecited in claim 1.